GitHub Linguist
is reasonably accurate at automatically detecting the percentages of each code language in Git tracked code.
However, as with any automatic coding language detection scheme, mis-detected languages occur.
This seems to happen for our uses most often with Matlab code.
Despite being in the top 10 STEM / data science languages, Matlab / GNU Octave *.m files can be detected as other languages such as Objective-C or Limbo.